Dear Jens,
I hope I can make a couple more remarks, and then I will keep quiet.
The first is that your suggestion that we do use Sohncke's name in
relation to these groups may still leave the impression that, as John put it
earlier, this name is just a "label". This is where I want to point out what
it is exactly that we owe Sohncke. It is not the bland definition of a list
of groups of Euclidean transformations with certain properties, printed in
some section of IT-A: it is a classification result, namely that if you look
for all the groups with those properties, there are only 65 types of them,
and here they are. So it is in that "65", that we take for granted because
we read it in the ITs, that Sohncke's contribution lies.
A second remark is about wanting to find where the attribute of
chirality (or pro-chirality) resides. As was pointed out, it is not the
groups themselves that have these attributes: it is objects in space on
which the groups act. A sensible adjective might therefore exist to
designate the 65, namely "chirality-preserving".
With best wishes,
Gerard.
--
On Fri, May 02, 2014 at 12:36:59PM -0700, Jens Kaiser wrote:
> Bernhard et al,
>
> >
> >
> > @ Jens:
> >
> > > I think the precise and correct term applicable to the "65" should
> > be pro-chiral spacegroups. They are not chiral by themselves, but
> > addition of "something" /allows/ for the creation of a chiral object
> > (i.e. the crystal).
> >
> > For a moment I though we have it…. but then the rest would be
> > anti-chiral?
>
> I never thought about it that way but actually, yes! You put something
> chiral into their AU and those little buggers go on and invert it. They
> are really anti-chiral. So we have the three groups chiral, prochiral
> and antichiral.
>
> I like the suggestion of calling the chiral and prochiral groups the
> Sohncke groups (beware everybody misspelled that poor guy, he has a ck
> in his last name). That keeps the history of our field in the
> expressions we use and might even inspire people to look up who the
> people were on whose shoulders we stand.
>
> Jens
>
> PS: I had to laugh when I looked him up on Wikipedia: "Leonhard Sohncke
> (22 February 1842 Halle – 1 November 1897 München) was a German
> mathematician who classified the 65 chiral space groups, sometimes
> called Sohncke groups." The German Wikipedia entry is much more
> complete.
> Also, I guess inspired by this thread, "anonymous" created an entry in
> Wikipedia "L.A. Sonke" - about 3h ago...
